BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Must be true CR

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 2326
Joined: Mon Jul 28, 2008 3:54 am
Thanked: 173 times
Followed by:2 members
GMAT Score:710

Must be true CR

by gmatmachoman » Sun Sep 13, 2009 10:22 am
The Rienzi, a passenger ship, sank as a result of a hole in its hull, possibly caused by sabotage. Normally when a holed ship sinks as rapidly as the Rienzi did, water does not enter the ship quickly enough for the ship to be fully flooded when it reaches the ocean floor. Full flooding can be achieved, however, by sabotage. Any ship that sinks deep into the ocean when not fully flooded will implode. Deep-sea photographs, taken of the sunken Rienzi where it rests on the ocean floor, reveal that the Rienzi did not implode.

Which one of the following must be true on the basis of the information above?



(A) The Rienzi was so constructed as to reduce the risk of sinking by impact.

(B) If the Rienzi became fully flooded, it did so only after it reached the ocean floor.

(C) If the Rienzi was not sunk by sabotage, water flooded into it unusually fast.

(D) If the Rienzi had sunk more slowly it would have imploded.

(E) The Rienzi was so strongly constructed as to resist imploding under deep-sea pressure.



OA[spoiler]:C[/spoiler]
Top
Source: — Critical Reasoning |
User avatar
GMAT Instructor
Posts: 9
Joined: Thu Aug 13, 2009 5:58 pm
Location: New York City
Thanked: 7 times

by brad@knewton » Wed Sep 16, 2009 7:47 am
Must be true questions (or Inference questions) test our ability to find an answer that has direct support from the statements provided. When tackling these questions, it's important to keep two things in mind:

1) Work slowly through the statements, considering how each relates logically to subsequent statements.

2) Incorrect answers very often seem like they could be true, but the mere possibility of validity is insufficient on the GMAT.

As far as the Rienzi is concerned we know the following:
It sank fast (cause unknown).
Normally when a ship sinks that fast it will not fully flood (one way to unsure full flood is sabotage).
A ship with incomplete flooding, if it sinks deep, will implode.
The Rienzi fully floded; it sank deep and did not implode (based on deep-sea photos).

Based on these statements only C is a valid inference. We don't know if sabotage was involved, but we do know if the Rienzi was a normal, fast sinking ship that sank deep, it would not have fully flooded and thus imploded. So, it is unusual (read: not normal) that it reached the ocean floor intact (unless of course sabotage was to blame).

(A) could be true, but we know nothing of the Rienzi's construction.

(B) cannot be true, because a ship that wasn't fully flooded by the time it reached the ocean floor would have imploded.

(D) could be true, but we know very little about how rate of sinking relates to implosion. Sinking more slowly doesn't necessarily mean that it sank slowly (just more slowly relative to the already fast rate).

(E) cannot be true. The statements tell us that any ship that is not full flooded will implode. You cannot argue with this evidence on test day. Take the statements given to you on the GMAT as true (at least to the author).

Hope that helps.
Brad McIlquham
Director of Curriculum, Knewton
https://www.knewton.com
Top
Legendary Member
Posts: 2326
Joined: Mon Jul 28, 2008 3:54 am
Thanked: 173 times
Followed by:2 members
GMAT Score:710

by gmatmachoman » Wed Sep 16, 2009 8:37 am
Thanks Brad :D

Clear Explanation...Cheers
Top
Post new topic Post Reply
• Page 1 of 1